Heretofore, chip wringers have successfully been utilized to separate coolant/lubricating fluid from scrap material. A typical application occurs following a lathe or other machining operation in which helical metal chips of varying discrete length are formed. The scrap chips and coolant to be separated are collected and directed to a centrifugal chip wringer. As the material is centrifuged, it moves up a rotating bowl wall and passes over a screen having openings therein. The fluid separates from the scrap solid chips, and passes through the screen openings where it then is collected, often for reuse. The dried solid chips continue to pass over the screen and thereafter are blown to a collecting station.
While centrifugal chip wringers have been quite satisfactory for separating fluids from chip materials, the wringers unfortunately have not heretofore served to efficiently separate what is referred to as xe2x80x9cswarf.xe2x80x9d Swarf is a slurry-like material generally generated in the course of a fine machining or grinding operation in which the scrap particles formed are quite fine as compared to the more discrete, finite-size chips generated, for example, in a lathe operation. Illustratively, in a grinding operation on steel stock, there is generated both a finished ground product as well as scrap product or swarf in which the swarf comprises (i) fine steel filings ground off the steel stock, (ii) fine pieces of metal or other material from the grinding tool, and (iii) lubricant/coolant. It has been found that in attempts to separate the coolant/lubricant from the swarf utilizing a conventional centrifugal chip wringer having a wedge wire screen, the swarf travels up the bowl wall of the centrifuge onto the screen wall. Unfortunately, it has been found that in most instances, the swarf material cannot be separated satisfactorily with a conventional screen known as a wedge wire screen in which a plurality of spaced members, such as illustrated in FIG. 2, are employed. It has been found that, after a relatively short period of time, the swarf plugs the screen openings such that either minimal separation occurs and/or the swarf solids pass through one or more screen openings with the fluid which also is undesirable. As a result, centrifugal separation of swarf has been an objective that has not heretofore been achieved with conventional centrifuge chip wringers having wedge wire screens.
What is desired is to utilize a centrifuge chip wringer that can successfully separate both chip and swarf materials. Further, it is desired to separate swarf material without excessive plugging of screen openings or having an excessive amount of the swarf solids passing through screen openings.
The present invention is directed to a centrifuge separating system which serves to separate swarf solids from lubricating and/or cooling fluids. Moreover, the system of the present invention serves to overcome the problems of swarf separation that heretofore existed while at the same time fulfilling the above-referenced desires for swarf separation.
Briefly, the invention comprises a centrifugal wringer utilizing a rotating bowl which directs swarf material upwardly along the internal surface of an outwardly and upwardly extending bowl wall. Swarf is defined herein as a combination of both fluids and solids in which the solids are relatively small, discrete, fine sand-like particles having a finite size unlike chips which are discrete generally elongated helical-shaped members. Typically, swarf comprises a composite of 40-50% total weight lubricant and 60-40% solids, the solids being granular or sand-like particles. Occasionally, it will be found that some chips are mixed in with the swarf.
The swarf passes over a screen attached to the rotating bowl. The screen has a plurality of spaced openings therein as disclosed in U.S. application Ser. No. 08/926,838, filed Sep. 10, 1997, and issued as U.S. Pat. No. 5,944,992 on Aug. 31, 1999 the entire disclosure of which is incorporated herein by reference.
As the swarf passes over the screen, the fluid separates from the solids and passes through the screen openings to a collecting station. The separated, relatively dry solids continue to pass over the screen and then are blown or otherwise directed to a collection station.
Accordingly, the invention is directed to the separation of swarf materials according to the step of delivering swarf to be separated to a centrifugal wringer device which includes a rotatable bowl and a rotatable screen attached to the top of the bowl. The screen is a cylindrical-shaped member formed of one or more components and comprises a plurality of spaced openings having a median width dimension of xe2x80x9cy,xe2x80x9d where xe2x80x9cyxe2x80x9d is approximately 0.030 to 0.040 inches on the inside swarf material-contacting surface of the screen when it is formed into its final formed cylindrical shape.
The screen openings are separated by a distance xe2x80x9cxxe2x80x9d between the center line from one opening to the center line of an adjacent opening. The screen is fabricated or otherwise made so that the spacing between the fluid passage openings xe2x80x9cxxe2x80x9d is maintained at a ratio of x/y with a ratio of at least 18/1, and preferably 100/1 or more being desired.
The method continues with the centrifuging of the swarf in the wringer, causing the swarf to be directed along the bowl wall where it then passes onto the screen; separating the fluid from the solids in the swarf by passing the fluids through the openings in the screen while passing the solids past the screen; and, directing the separated swarf fluids to a first desired location and directing the separated swarf solids to a second desired location.
The system of the invention serves to separate swarf fluids from swarf solids satisfactorily.
Further, the screen can be cast or fabricated in one piece or, if desired, the screen can be formed of a plurality of screen segments. When made in one piece, the screen can be made sufficiently flexible such that it can be wrapped in a circular shape to fit into a centrifuge. Further, the screen of the invention can be formed with a plurality of slots or openings of differing shapes. Because the screen can be cast or fabricated with the desired surface distance/opening width ratio, the need for forming a screen out of a plurality of drawn bars is obviated.